Laravel giving error Undefined property: stdClass::$latitude - php

Question

I am trying to use a package a link! and when after installation I tried to run this project it just failed and started giving me the error of Undefined Property.
So if anyone could help me out.
Its getting harder to complete my project with these errors
IPstack.php
namespace Voerro\Laravel\VisitorTracker\Geoip;
class Ipstack extends Driver
{
protected function getEndpoint($ip)
{
$key = config('visitortracker.ipstack_key');
return "http://api.ipstack.com/{$ip}?access_key={$key}";
}
public function latitude()
{
return $this->data->latitude;
}
public function longitude()
{
return $this->data->longitude;
}
public function country()
{
return $this->data->country_name;
}
public function countryCode()
{
return $this->data->country_code;
}
public function city()
{
return $this->data->city;
}
}
Driver.php
namespace Voerro\Laravel\VisitorTracker\Geoip;
use Voerro\Laravel\VisitorTracker\Models\Visit;
use GuzzleHttp\Client;
abstract class Driver
{
/**
* Holds data fetched from a remote geoapi service
*
* #var Object
*/
protected $data;
/**
* Fetch data from a remote geoapi service
*
* #param Voerro\Laravel\VisitorTracker\Models\Visit $visit
* #return $this
*/
public function getDataFor(Visit $visit)
{
$client = new Client();
$response = $client->get($this->getEndpoint($visit->ip));
if ($response->getStatusCode() == 200) {
$this->data = json_decode($response->getBody()->getContents());
return $this;
}
return null;
}
/**
* Returns an endpoint to fetch the data from
*
* #param string $ip IP address to fetch geolocation data for
* #return string
*/
abstract protected function getEndpoint($ip);
/**
* Returns latitude from the fetched data
*
* #return string
*/
abstract public function latitude();
/**
* Returns longitude from the fetched data
*
* #return string
*/
abstract public function longitude();
/**
* Returns country from the fetched data
*
* #return string
*/
abstract public function country();
/**
* Returns country code from the fetched data
*
* #return string
*/
abstract public function countryCode();
/**
* Returns city from the fetched data
*
* #return string
*/
abstract public function city();
}
So here is the driver.php if you could find the error.